C-reactive protein (CRP) concentration in serum/plasma
This test measures the level of C-reactive protein, a substance produced by the liver in response to inflammation in the body.
["CRP helps identify inflammation, which can signal infections, injuries, or other health conditions."]
Key facts at a glance
- LOINC
- 95638-3
- Short code
- CALEV
- Synonyms
- CEV NAb Titr Spec Nt
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top tube; transport to laboratory at 2-8°C
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Neutralization test (Virus neutralization assay)
- CPT
- 86651
- SNOMED
- 12245004
- Specimen volume
- 1-2 mL of serum (minimum 0.5 mL)
- Stability
- Serum stable at 2-8°C for 7 days; for longer storage, freeze at -70°C or below; avoid repeated freeze-thaw cycles
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 72–168 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order a CRP test to check for signs of inflammation, monitor chronic conditions like arthritis or heart disease, or evaluate symptoms such as fever, pain, or swelling. It can also help assess how well a treatment is working or detect infections before other symptoms appear.
What to Expect Before the Test
No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if it involves drawing blood from a vein. If you’re taking blood from a fingerstick (e.g., for glucose monitoring), no fasting is required.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a brief pinch, but the procedure is quick. If you’re nervous, let them know—they can use a numbing cream or take extra time to make it more comfortable.
What Are Possible Results?
Results are not typically shared as a single number but are compared to a general range of what’s considered normal for healthy adults. Higher than normal levels may indicate inflammation, while very low levels might suggest an underlying issue like an immune disorder.
Reference range
Titer < 1:10 or negative; A fourfold rise in titer between acute and convalescent specimens is considered diagnostic of recent infectionN/A
No fasting required. Acute specimen should be collected within the first week of illness onset; convalescent specimen should be collected 2-4 weeks after the acute specimen.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
CRP is a marker of acute-phase reactant, meaning its levels rise in response to inflammation caused by infections, injuries, autoimmune diseases, or other stressors. Chronic elevations may signal conditions like rheumatoid arthritis, cardiovascular disease, or inflammatory bowel disease. However, CRP alone cannot diagnose a specific condition—it’s often used alongside other tests and clinical findings.
Short name
CRP (Serum/Plasma)
Frequently asked questions
How long does it take to get my CRP test results?
Can I eat or drink before this test?
Does CRP test hurt?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy